A Preliminary Climatology of U.S. Ice Storm Frequency and a Comparison Between Northeast U.S. Ice Storm Frequency and Teleconnections

Carly Kovacik
OU School of Meteorology

30 October 2013, 3:00 PM

Winter weather has had a pronounced impact on both lives and property across the contiguous United States for many years. Numerous studies have been conducted on these types of events to better understand the dynamical aspects, synoptic evolution and corresponding mesoscale features, as well as the associated hazards, to improve short-term forecasts. Many of these studies have focused solely on snowstorms, blizzards, or a particularly severe winter weather event. Mixed precipitation events and ice storms are also of great hazard during the winter months.

Ice storms are dangerous and destructive winter weather events. Freezing rain and freezing drizzle produce hazardous conditions with significant societal impacts that can last from several days to several weeks. Industries that are impacted by these events include power, transportation, aviation, insurance, and public safety. Minor glaze accumulation causes pedestrian and traffic accidents, while severe ice storms cause power outages, delays and closings of ground and air transportation, property damage, and physical injury.

A preliminary climatology of ice storm frequency was developed across the contiguous United States for the winter seasons (December, January, and February) during 1966-1977 and 1998-2011. These periods were chosen because they were associated with notable changes in global temperature anomalies associated with El Nino-Southern Oscillation (ENSO). The most notable shift in ice storm frequency between the two time periods was observed over the northeast U.S. and hypothesized to be associated with changes in global atmospheric circulations. A climatology of Northeast U.S. ice storms from 1966-2011 was then compared to phase changes of the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), the Atlantic Multidecadal Oscillation (AMO), and ENSO. Qualitative conclusions regarding a potential association between ice storm frequency across the Northeast and global climate anomalies, along with important inconsistencies encountered within archived ice storm data will also be discussed.

**Time permitting the results of a comparison between Oklahoma ice storm frequency and global climate anomalies will also be shown.

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